I will answer you with my experience, and what other have told me and what I have seen. Also I know what it's like to work with people you see everyday and people you simply met on the internet.
First I will answer to "It's something common isn't it ?" Well, yes and no. It's more common than what I might believe (I can think of already a few people who made a game by themself), but no it isn't as common as to say that no one has never once work with someone else, see what I mean ? It's not common for someone to not have at least one experience of working with someone even if it's just hobby, but there's tend to be a lot more people doing their own thing alone those past years with how it is easy to learn Game development in general (by this I mean, it's easy to learn information freely or not through internet).
However, you are limited as to what you can do and how much time you can do it. To do something all alone means you have to learn everything (and believe me, when you think you know something you have only scratched the surface), that everything need to work well together, and how long it will take to create that everything will depend on three things : "how long does it takes you to learn this" , "how much time can/will you give it" "how many mistakes will you do before being able to realise what you want" . And of course, you will be limited to your knowledge. In overall, you can work alone if you wish to, and I think it's a good thing to be interested in everything little by little, but don't try to do grand thing at first and simply find your flow. Anyway, back to the topic.
How was it in overall ? Well, going to be honest, not that good, but not that terrible either. I found out that there's some people that are rare pearl, that know how to do everything, other that are learning but have their heart to the right place with a burning desire of learning everything they can, while other are simply incomptent and sometimes terrible people to other.
My words may seem harsh when I say some people are incompetent, but honestly some truly are; I don't mean specifically their skill; some of them are self taught some are not who cares, but they refuse to listen to other; or are egocentric and everything they do tend to not work or simply are not good idea (or it's not pleasant to work with them). Some people simply aren't made to be in video game, or to be in your group because they don't fit or else. I've had a really bad project because I had also people I could not count on, of course I did mistakes but not being able to trust each other because of this or that well the worst mistake without a doubt, it wasn't a pretty sight at the end.
I would say, you want a good team ? Have an excellent communication. Even if your vibe or else do not fit with them, it doesn't matter, communicate well as long as you share the same point of view for your project and are respectful and listen to each other it should go well, honestly you need to be able to trust your team or duo, if however you know after some time that you can't count on them well, you either disband the team or duo or if you have no choice you try to find way to work with them. Depend of the project, if it's pro or not and how many people are here, but if you are not a lead you can't fire someone, and to fire someone there's need to be proof and complain anyway let's go back to internet.
On internet, people sometimes will ghost you that it's intentional or not it will happens so honestly considering you don't know that person, don't know their skill, don't know how to judge their skill, don't know w h a t their skill are or who they are it's honestly a big fifty-fifty. I do think that if you make a post about wanting to work for a team and people answer you on that post, it means they want to so if something goes wrong it might be that their skill either are not that good or it's not nice to work with them; even if someone is kind, if they don't listen to you or worse if you don't share the same view of what something could be, you're in for a ride. On this, it's good to have clashing idea, it's not good if that clashing idea is the opposite of what you see for the game; especially if it's the beginning (pre-preeeeee production) or if you are only two.
To have a good note, because it feels like there had been only negativity in my post, it's not that there's only negativity in working with people but most people simply see the good and not really the bad, because honestly the good is what you expect, there's good people working in video game, passionate be it in real life, on the internet, as a hobby or as a professional, you'll meet a lot of people that share the same passion as you and many are lending each other their hand; it's honestly a wonderful thing to be apart of, a wonderful thing to see. You might connect with people, less with other but still work and admire what they do; it's a never ending cycle.
I've spoken a lot about the human side of a team, on the techincal side let me tell you it will be a mess. Communication is the key, but sometimes when you don't know how something work there will be a mistake. Working as a duo is well, fine on the technical part; you are only two and if you have connected well it will be fun. Now working in a team as many as 8, when you take back what I said about everyone skill there is some thing that don't work. The skill are too different, or simply people who have never worked with each other need to adapte. It's a mess when it's a programmer with a programmer, there's a reason why a programmer should never go into another programmer's code AND a reason why in video game an important part of our job is also tied to having good documentation so that the communication works. On the artist side, it's the version of "a programmer in a programmer's code", people will have to work with your work so any mistake will fall on you without.... good communciation (Take a shot each time I say communication). But in overall it's a big mess as at the beginning because it's the unknown and everyone need to adapt and see who is "good" who is "not". The most difficult part has always been communication between programmers and artist, because when you create a video game there's soooo many parameters you need to know that are more than simply doing 3D, or doing concept or doing code (I could go for hours about this), that simply are technical. It's good to know how things work on each side.
I wanted to finish by saying that when you are many on a team, you need a lead, someone who will have the final decision. A good lead isn't someone who give order and bark at you, it's someone who also care for the project and know how to get things done (which mean understanding how each people are and work to know what can be done or can't). A good lead is, I don't know, honestly an envoy from god because they can carry the team, the moral and have the competence to do so. A bad lead will simply make things go sour faster.
I will be honest when saying sometimes things don't work and it's for the best; just as sometimes things work and it's for the best. I don't want to paint a grim picture of working with a team because it's not; but I thought I should focus those point because as I said earlier, the good is exactly what you think it is, the bad you may not know until you experience it. I simply want to be as honest as possible. It's a messy thing, that sometimes is disastrous but also an amazing and fun experience that will teach you so many things no matter the outcome and will let you meet amazing people !
(I apologize for the long message !)
